2013-08-02  Antonio Gomes  <a1.gomes@sisa.samsung.com>

        conformance/buffimgs/cl_commandQueue_enqueueCopyImageToBuffer.html crashes safari
        Issue #263

        Reviewed by Igor.

        Passing an invalid object to 'region' fails to
        create a Int32Array. Null check it.

        All other method check it, but this one.

        * Modules/webcl/WebCLCommandQueue.cpp:
        (WebCore::WebCLCommandQueue::enqueueCopyImageToBuffer):